Surprisingly, it has been discovered that the underlying structure of user movie rating data has almost low rank structure.
It means that, if the entire matrix was available the column space of it would be low rank subspace with additional noise structure on it.
Hence, this column space could be formalized as the most columns those are belong to the highest values of singular values.
Since then, low-rank estimation has gained attention from the researchers to find an efficient way to estimate this structure [1]}.
